#include <stdio.h>
#include <string.h>

int main()
{
  FILE *pf = fopen("log.txt", "w");
  const char *msg = "hello bit\n";
  
  int cnt = 5;
  while(cnt--)
  {
    fwrite(msg, strlen(msg), 1, pf);
  }
  return 0;
}
